synesthesia-snippet-fragment-shader.glsl

#ifdef GL_ES
precision lowp float;
#endif

#define TWO_PI 6.28318530718

uniform sampler2D videoTexture;
varying vec2 vUv;

uniform vec3 colorA;
uniform vec3 colorB;

float blendOverlay(float base, float blend) {
  return base<0.5?(2.0*base*blend):(1.0-2.0*(1.0-base)*(1.0-blend));
}

vec3 blendOverlay(vec3 base, vec3 blend) {
  return vec3(blendOverlay(base.r,blend.r),blendOverlay(base.g,blend.g),blendOverlay(base.b,blend.b));
}

vec3 blendOverlay(vec3 base, vec3 blend, float opacity) {
  return (blendOverlay(base, blend) * opacity + base * (1.0 - opacity));
}

float luminance(vec3 c) {
    return dot(c, vec3(0.22, 0.707, 0.071));
}

void main() {

  vec2 st = vUv;
  vec3 color = mix(colorA, colorB, st.x);
  vec3 tex = texture2D(videoTexture, vUv).rgb;
  float lum = luminance(tex);
  tex = mix(tex, vec3(lum), 1.0);
  vec3 mixed = blendOverlay(tex, color, 0.5);

  gl_FragColor = vec4(mixed, 1.0);
}